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M15
CGMC M15A1

Multiple Gun Motor Carriage M151-7

M15: General
Date of first acceptance February 1943 Total acceptances 600
Manufacturer Autocar Co. Crew 7 men
M15: Dimensions
Combat weight 20,000lbs
9000kg
Height 104"
264cm
Length with roller 236.5"
600.7cm
Gun overhang forward 0"
Width 98"
250cm
Front tread 64.5"
164cm
Rear tread 63.8"
162cm
Wheelbase 135.5"
344.2cm
Ground clearance 11.2"
28.4cm
M15: Armament
Type Mount Ammunition Traverse Elevation
37mm Gun M1A2 M42 240 rounds 360°
(manual)
+85° to 0°
(manual)
Two .50cal M2HB MG M42 3400 rounds 360°
(manual)
+85° to 0°
(manual)
Rangefinder
Sighting system M6
M15: Armor
Assembly
Bolting
Hull
Rolled face-hardened steel
Location Thickness Angle from vertical
Radiator louvres .25"
.64cm
26°
Windshield cover .50"
1.3cm
25°
Sides .25"
.64cm
Rear .25"
.64cm
Hood top .25"
.64cm
83°
Turret
Rolled face-hardened steel
Location Thickness Angle from vertical
Shield .25"
.64cm
M15: Automotive
Engine White 160AX; 6 cylinder, 4 cycle, in-line gasoline
Horsepower Net: 147@3000rpm Torque Net: 325 ft-lb@1200rpm Fuel capacity 60gal
230L
Transmission Spicer 3461 constant mesh, 4 speeds forward, 1 reverse
Steering Steering wheel
M15: Suspension
Type Road wheels Track return rollers
Front: Semi-elliptic longitudinal leaf spring
Rear: Vertical volute spring
Front: Steel ventilated disc
Rear: 1 bogie/track;
4 dual/bogie
1 dual/track
Drive sprockets Idlers Shock absorbers
18-tooth front drive Spring-loaded at rear of track On front wheels
M15: Track
Center guide band type
Width 12"
30cm
Pitch 4"
10cm
Pitches/track 58 Track ground contact length 46.75"
118.7cm
M15: Performance
Max level road speed 45mph
72kph
Max grade 60%
Max vertical obstacle 12"
30cm
Min turning diameter 59'
18m
Max fording depth 32"
81cm
Cruising range ~200mi, roads
~320km, roads

The M15 was based on the MGMC T28E1. Modifications included that air-cooled MGs were subsituted for the earlier vehicle's water-cooled weapons, the lead setter's handwheels were reversed, larger handwheels were mounted, the vertical handwheel was mounted parallel to the guns, a seat for another lead setter was added, empty casings were enabled to be corralled and removed, the boresighting procedure was improved, and an armored enclosure open at the top and rear was mounted around the gun mount. There was also initially an armored gun shield through which the gun barrels protruded, but this was later removed to improve the gun crew's visibility. The guns still could not be depressed below +20° when aimed over the cab.

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Combination Gun Motor Carriage M15A11-7

M15A1: General
Date of first acceptance October 1943 Total acceptances 1652
Manufacturer Autocar Co. Crew 7 men
M15A1: Dimensions
Combat weight 20,000lbs
9000kg
Height 104"
264cm
Length with roller 236.5"
600.7cm
Gun overhang forward 0"
Width 98"
250cm
Front tread 64.5"
164cm
Rear tread 63.8"
162cm
Wheelbase 135.5"
344.2cm
Ground clearance 11.2"
28.4cm
M15A1: Armament
Type Mount Ammunition Traverse Elevation
37mm Gun M1A2 M54 200 rounds 360°
(manual)
+85° to -5°
(manual)
Two .50cal M2HB MG M54 1200 rounds 360°
(manual)
+85° to -5°
(manual)
Rangefinder
Computing sight M14
M15A1: Armor
Assembly
Bolting
Hull
Rolled face-hardened steel
Location Thickness Angle from vertical
Radiator louvres .25"
.64cm
26°
Windshield cover .50"
1.3cm
25°
Sides .25"
.64cm
Rear .25"
.64cm
Hood top .25"
.64cm
83°
Turret
Rolled face-hardened steel
Location Thickness Angle from vertical
Shield .25"
.64cm
M15A1: Automotive
Engine White 160AX; 6 cylinder, 4 cycle, in-line gasoline
Horsepower Net: 147@3000rpm Torque Net: 325 ft-lb@1200rpm Fuel capacity 60gal
230L
Transmission Spicer 3461 constant mesh, 4 speeds forward, 1 reverse
Steering Steering wheel
M15A1: Suspension
Type Road wheels Track return rollers
Front: Semi-elliptic longitudinal leaf spring
Rear: Vertical volute spring
Front: Steel ventilated disc
Rear: 1 bogie/track;
4 dual/bogie
1 dual/track
Drive sprockets Idlers Shock absorbers
18-tooth front drive Spring-loaded at rear of track On front wheels
M15A1: Track
Center guide band type
Width 12"
30cm
Pitch 4"
10cm
Pitches/track 58 Track ground contact length 46.75"
118.7cm
M15A1: Performance
Max level road speed 45mph
72kph
Max grade 60%
Max vertical obstacle 12"
30cm
Min turning diameter 59'
18m
Max fording depth 32"
81cm
Cruising range ~200mi, roads
~320km, roads

Supplies of the combination gun mount M42 ran low, so the upper portion of the 37mm gun carriage M3A1 was substituted, creating the combination gun mount M54. The position of the guns was reversed on this new mount, with the .50cal MGs mounted below the 37mm gun. The top armor flaps on either side of the guns were hinged and could be folded down to improve visibility. A rail was provided at the rear of the mount to aid in mounting and dismounting the vehicle, and the 37mm gun loader and lead setter were also provided with platforms.

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References

  1. Hunnicutt, R.P. Half-Track: A History of American Semi-tracked Vehicles. Navato, CA: Presidio Press, 2001. Reprinted from Half-Track, R.P. Hunnicutt ©2001, available from Presidio Press, 505B San Martin Drive, Suite 160, Navato, CA 94945.
  2. Doyle, David. U.S. Half-tracks: The Development and Deployment of the U.S. Army's Half-track Based Multiple Gun Motor Carriages and Gun Motor Carriages, Part two. Ed. Pat Stansell. Delray Beach, FL: The Ampersand Publishing Group, Inc., 2016.
  3. TM 9-710 Basic Half-Track Vehicles (White, Autocar, and Diamond T). Washington, DC: War Department, 23 February 1944.
  4. Crismon, Fred W. U.S. Military Tracked Vehicles. Osceola, WI: Motorbooks International, 1992.
  5. Chamberlain, Peter, and Chris Ellis. British and American Tanks of World War Two. Frome, England: Cassell & Co., 2000.
  6. Standard Nomenclature List G-102. 30 Sep 1943.
  7. Siemers, Cary. "USA's Half Track Gun Motor/Mortar Carriages." World War II Tanks & Vehicles and Advanced Squad Leader. 4 Jul 2001. 19 Sep 2001 <http://www.siemers.com/wwii/USA/GunMotorCarriage.htm>.

Last updated 22 May 2016.
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© Copyright 2001-16 Chris Conners